Resealable thermoplastic elastomer articles

ABSTRACT

A thermoplastic elastomer (TPE) composition is provided which contains a blend of a hydrogenated styrenic block copolymer (SBC) having a number average molecular weight (Mn) greater than about 200,000 Daltons (Da), a polypropylene, a mineral oil, and at least one filler. The composition has a hardness less than about 80 Shore A and is resealable. An article produced from such a TPE composition reseals itself so as to exhibit no leakage after puncture. A method for preventing leakage in an elastomeric article involves providing an elastomeric article formed from the TPE composition, puncturing the elastomeric article by inserting a sharp object, and removing the sharp object; the article reseals itself such that no leakage occurs from the punctured article after removal of the sharp object.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional application of U.S. Ser. No. 13/266,259 filed Oct.26, 2011, which is a Section 371 of International Application No.PCT/US2009/044665, filed May 20, 2009, which was published in theEnglish language on Nov. 25, 2010, under International Publication No.WO 2010/134915 A1, and the disclosures of which are incorporated hereinby reference.

BACKGROUND OF THE INVENTION

The present invention is directed to a thermoplastic elastomer (TPE)composition, particularly for use in penetrable articles.

TPEs are elastic, flexible polymers that exhibit similar physicalproperties to elastomers, but which are recyclable and easier toprocess. Compositions made from TPEs are widely used in applicationswhich have traditionally employed silicones (polysiloxanes) and otherthermoset rubbers, which do not melt. Articles can be formed from TPEcompositions to have similar physical properties as their elastomercounterparts while also being injection moldable, which reduces the costof production and allows the TPE article to be recycled. TPEcompositions can thus be injection molded to form articles such asseals, gaskets, septa, caps for bottles, plugs, medical devices, andother objects that might otherwise be formed from silicone.

TPEs are easier to process than elastomers because they are crosslinkedby non-covalent bonds (secondary interactions). At room temperature,TPEs behave like crosslinked elastomers. However, at elevatedtemperatures, they behave as linear polymers. Thus, TPEs, unlikeelastomers, have reversible properties as the temperature increases ordecreases. The reversible crosslink allows articles formed from TPEcompositions to be melted and reformed.

A TPE can be formed from block copolymers or from blocks of homopolymerhaving various tacticity within its chains. The elastomeric propertiesof thermoplastic elastomers result from the phase separation between theblocks. One of the blocks forms a continuous phase, which providesrubbery properties, while another block is glassy or crystalline. Theglassy/crystalline blocks provide the crosslinks for the blocks of thecontinuous phase.

In the case of block copolymers, styrene is frequently used as theglassy/crystalline block that crosslinks with other polymer blocks.Block copolymers that contain styrene are known as styrenic blockcopolymers, or SBCs. Examples of SBCs include SBS block copolymers(styrene-butadiene-styrene), SIS block copolymers(styrene-isoprene-styrene), and SI/BS block copolymers(styrene-isoprene/butadiene-styrene). SBS, SIS, and SI/BS blockcopolymers can be hydrogenated to yield the hydrogenated styrenic blockcopolymers (HSBCs), such as SEBS (styrene-ethylenebutylene-styrene),SEPS (styrene-ethylene/propylene-3-methylbutene-styrene), SEEPS(styrene-ethylene-ethylene/propylene-styrene), and SIPS(styrene-isoprene-styrene block copolymer).

In general, TPE compositions are formed by blending TPEs, polyolefins,and additives, such as plasticizers, stabilizers, and lubricants. Thepolyolefin functions as the continuous phase of the TPE composition.Polypropylene is the polyolefin typically selected for the continuousphase of many TPE compositions.

It has been found that prior art TPE compositions cannot simultaneouslyprovide desired levels of hardness, temperature stability, moldability,and tensile strength while also exhibiting satisfactory resealproperties. It would be desirable to be able to produce TPE compositionswhich overcome such limitations.

BRIEF SUMMARY OF THE INVENTION

According to a first aspect, the present invention provides for athermoplastic elastomer composition comprising a blend of a hydrogenatedstyrenic block copolymer having a number average molecular weightgreater than about 200,000 Daltons, a polypropylene, a mineral oil, andat least one filler. The thermoplastic elastomer composition has ahardness of less than about 80 Shore A and is resealable.

According to another aspect, the present invention provides a resealablethermoplastic elastomeric article. The article comprises a blend of ahydrogenated styrenic block copolymer having a number average molecularweight greater than about 200,000 Daltons, a polypropylene, a mineraloil, and at least one filler, and has a hardness of less than about 80Shore A.

According to a further aspect, the present invention provides a methodfor preventing leakage in a punctured elastomeric article comprising:

-   -   (a) providing an elastomeric article comprising a thermoplastic        elastomer composition comprising a blend of a hydrogenated        styrenic block copolymer having a number average molecular        weight greater than about 200,000 Daltons, a polypropylene, a        mineral oil, and at least one filler; wherein the thermoplastic        elastomer composition has a hardness of less than about 80 Shore        A;    -   (b) puncturing the elastomeric article by inserting a sharp        object; and    -   (c) removing the sharp object;        wherein the article reseals itself such that no leakage occurs        from the punctured article after removal of the sharp object.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a TPE composition having goodreseal properties. Articles formed from such a composition may bepenetrated or punctured by a sharp object, such as a needle, cannula, orIV spike, with no leakage, even after the articles have been subjectedto autoclaving. The TPE composition is applicable for the formation ofmedical articles such as penetrable septa, stoppers, bottle caps, andplugs.

More specifically, the present invention provides for TPE compositionsthat include a thermoplastic elastomer component (TPE component), apolypropylene, a mineral oil, and at least one filler. Such compositionspreferably have a hardness of less than about 80 Shore A and exhibitexcellent reseal properties. That is, articles prepared from suchcompositions exhibit no leakage after being punctured with a sharpobject. Further, these reseal properties are exhibited by the TPEcompositions even after autoclaving.

After an article produced from the inventive TPE composition ispunctured, such as with a needle, IV spike, cannula, or the like, theopening that is formed reseals automatically due to the self-sealingnature of the TPE composition such that no leakage occurs from thepunctured article. This property is important for articles that are tobe punctured in medical or scientific research use. For example, if apuncture is made in the cap of a bottle filled with liquid, it could bedangerous if the liquid sprayed from the resulting hole after removal ofthe needle from the cap. This could occur if insufficient resealabilitywere provided by the material used to form the bottle cap.

TPE Component

The advantageous properties exhibited by the TPE compositions areachieved in part by including a TPE component containing a hydrogenatedstyrenic block copolymer (SBC) having a number average molecular weight(Mn) of at least about 200,000 Daltons. As demonstrated below, includingsuch a high molecular weight hydrogenated SBC in the TPE composition isimportant for maintaining excellent reseal properties after autoclaving.The use of a high molecular weight hydrogenated SBC also provides theTPE composition with a desirable hardness level below about 80 Shore A,more preferably less than about 65 Shore A, most preferably less thanabout 50 Shore A.

Exemplary hydrogenated SBCs for use in the TPE component include SEBS,SIBS, and SEEPS. For example, a currently preferred SEBS copolymer isKRATON® G1633 polymer, which has a number average molecular weight ofmore than 200,000 Daltons and is supplied in fluffy crumb form by theKraton Polymers Group of Companies. Other SEBS block copolymers, such asKRATON® G1651, which have lower molecular weights, do not provide thedesired reseal properties in the resulting TPE composition. ExemplarySEEPS copolymers are Septon 4077 and Septon 4099, commercially availablefrom Kuraray America, Inc. It is also within the scope of the inventionto include more than one hydrogenated SBC in the TPE component, providedthat the number average molecular weight of each SBC is greater thanabout 200,000 Daltons.

Polypropylene Component

The polypropylene component provides a continuous phase in the TPEcomposition of the present invention. The amount of polypropylenecomponent in the TPE composition of the present invention is preferablyabout 5 to 50 pph (parts per hundred), more preferably about 10 to 50pph, and most preferably about 10 to 35 pph, relative to 100 parts ofthe SBC TPE component. For the purposes of this disclosure, the term“pph” may be understood to mean “parts per 100 parts of the SBC TPEcomponent.”

The melting point of the polypropylene component is typically above 130°C. The polypropylene may be selected from homopolymers and copolymers ofvarious tacticity, including clarified random polypropylene copolymers,clarified polypropylene homopolymers, and combinations thereof

Examples of random polypropylene copolymers include copolymers ofpropylene and an α-olefin, such as ethylene or 4-methyl-l-pentene(PP9074MED, supplied by ExxonMobil

Chemical). Suitable clarified polypropylene homopolymers include, forexample, Purell HP 570M from Bassell, which has a melting point of 164°C., and Total Petrochemicals M3282MZ, which has a melting point of 153°C. The polypropylene component typically has greater than 70 percentisotactic linkages, and its melt flow rate is in the range of 10 to 100g/10 min in accordance with ASTM D1238.

Mineral Oil Component

The TPE composition further comprises a mineral oil as a lubricant. Themineral oil assists in providing the desired reseal properties, and alsoeases the release from a mold cavity of an article molded from the TPEcomposition. The lubricant also provides a slippery feel to the moldedarticle, which would otherwise be tacky due to the physical propertiesof the block copolymer.

Appropriate mineral oils for inclusion in the present invention include,for example, paraffinic hydrocarbons such as Primol 352, a purifiedmixture of liquid saturated hydrocarbons that is commercially availablefrom Exxon Mobil, and Citgo Duoprime Oil 350 (Citgo PetroleumCorporation). The mineral oil is preferably a paraffinic oil, morepreferably a high viscosity paraffin oil, because such oils provide thedesired color and odor characteristics. The mineral oil must be purifiedso that the resulting TPE composition will pass the stringentpharmacopeia extraction tests that are required of materials for medicaluse.

The mineral oil is preferably contained in the TPE composition in anamount of about 10 to 400 pph, more preferably about 50 to about 300ppm, most preferably about 100 to 200 pph.

Filler Component

Finally, the TPE compositions of the present invention contain at leastone filler. Appropriate fillers include, for example, calcium carbonate,clay, talc, silica, and carbon black, but other similar fillers known inthe art or to be developed would also be appropriate for inclusion inthe TPE compositions. The filler(s) are preferably contained in thecomposition in an amount of about 10 to about 120 pph, more preferablyabout 20 to 110 pph, most preferably about 30 to 110 pph. Theincorporation of a filler has been shown to have a positive effect onthe reseal properties of the composition, particularly afterautoclaving.

Optional Components

The TPE compositions of the present invention may also include astabilizer component. Stabilizers applicable to the present inventioninclude antioxidants, such as hindered phenols. Exemplary stabilizersinclude those commercially known as IRGANOX® 1010, IRGANOX® 1076, andIRGANOX® PS-800 (distearylpentaerythritol diphosphite) of Ciba SpecialtyChemicals and CYANOX® LTDP (Dilaurylthiodipropionate), commercially soldby Cytec. These antioxidants trap free radicals formed upon heating inthe presence of oxygen and prevent discoloration or changes in themechanical properties of the TPE composition.

If included, the amount of stabilizer contained in the TPE compositionsof the present invention is preferably in an amount of about 0.01 to 2.0pph, more preferably about 0.05 to 1.5 pph, and most preferably about0.1 to 1.0 pph.

It is also within the scope of the invention to include colorants knownin the art or to be developed for use in elastomer compositions. Thecolorant may be selected based on the desired overall appearance of theTPE composition or articles to be made therefrom. For example, if a graycolor is desired, Gray 3239, a gray color concentrate in HDPE, would beappropriate. The amount of colorant included in the composition isdependent on the color concentrate and may be determined on acase-by-case basis.

In producing the TPE compositions of the present invention, thecomponents for the TPE composition may be blended by any known method.To obtain a homogeneous TPE composition, the above mentioned componentsmay be dry blended, prior to melt-kneading, using a mixer, such as aHenschel mixer, a tumbler, a ribbon blender, or the like, and thenmelt-kneaded using a conventional kneader, such as a mixing roll, akneader, a Banbury mixer, an extruder, or the like. Examples of moldingmethods useable for forming articles from the TPE composition of thepresent invention include injection molding, extrusion molding,compression molding, blow molding, rotary compression molding, and thelike. It is within the scope of the invention to produce a wide range ofarticles from the TPE compositions of the present invention, includingwithout limitation medical devices, septa, closures, plugs, bottle caps,etc. However, the TPE composition according to the invention hasparticular applicability to the production of articles that will besubjected to both autoclaving and puncture, such as penetrable septa andcaps for medical bottles.

EXAMPLES Experimental Procedure

Test plaques were formed from the TPE formulations described in theexamples below. The test plaques were compression molded at 350° F.(177° C.), a heating cycle of 5 minutes, a hot compression cycle of 1.5minutes, and a cooling cycle of 17 minutes. The following tests wereperformed on the test plaques: ASTM D412 (tensile strength), ASTM D395(compression set), and ASTM D2240 (hardness). In addition, percentelongation of the test samples was measured after tensile testing, andtensile stress at elongation of 100%, 200%, and 300% was evaluated. Thecompression set of each test plaque was also determined afterautoclaving at 121° C. for one hour using two different conditions:cooling to room temperature under compression and cooling to roomtemperature without compression.

Reseal properties of the TPE compositions were assessed as follows. TheTPE was molded to an IV septum and assembled on a cap, which wasassembled onto an IV bottle that was half filled with water. An IV spikehaving a 6 mm OD was inserted through the TPE septum, thus generatingpressure inside the bottle. Depending on the experiment, the IV spikewas pulled out at a pressure of 200 mbar (20 kilopascal) or 450 mbar (45kilopascal) and the reseal rating determined on a relative scale of “0”to “4” as follows. “0” meant that no drop of water appeared from thecap, “1” indicated that a single water drop adhered to the cap, “2”meant that a single drop of water fell off the cap, “3” indicated thatmultiple drops of water fell off the cap, and a ranking of “4” indicatedthat water sprayed from the bottle after removal of the spike. Thereseal test was performed on the TPE samples both before and afterautoclaving at 121° C. for one hour. Each reseal test was performed onmultiple samples.

Table 1 below provides a list of the components used to form the TPEcompositions in the following examples.

TABLE 1 Components of TPE Compositions Component Trade Name GenericName/Description SBC TPE KRATON ® 1633 SEBS (Mn of greater than about200,000 Da) SBC TPE KRATON ® 1651 SEBS (Mn of less than about 200,000Da) Polypropylene Purell HP 570M Polypropylene (melt flow rate of 7.5g/10 min) Colorant Gray 3239 Gray color concentrate in HDPE FillerOmyacarb 2-GU Calcium carbonate Filler Mistron CB Talc Mineral OilPrimol 352 a purified mixture of liquid saturated hydrocarbonsStabilizer IRGANOX ® PS 800 Distearylpentaerythritol (antioxidant)diphosphite Stabilizer IRGANOX ® 1010 Methylene (3,5-di- (antioxidant)tert-butyl-4- hydrozyhydrocinnamate) methane

Example 1 TPE Compositions A-D

Four different TPE compositions (labeled A through D) were prepared todemonstrate the effect of molecular weight of the hydrogenated SBCcomponent on the reseal properties of the composition. Each of thecompositions contained polypropylene, mineral oil, filler, ahydrogenated SBC, colorant, and stabilizers.

The TPE compositions each contained the same type and amount of thepolypropylene, mineral oil, filler, colorant, and stabilizers, as shownin Table 2 below. Each of the TPE compositions A to D also contained 100total parts of hydrogenated SBC component selected from KRATON® G1633 (ahigh molecular weight SEBS having a number average molecular weight ofat least about 200,000 Daltons) and KRATON® G1651 (a lower molecularweight SEBS having a number average molecular weight of less than about200,000 Daltons). The amount of each SBC in Compositions A to D isspecified in Table 2 below. The TPE compositions were mixed in a labtwin screw extruder (PRISM TST-24TC) with a batch size of 50 lbs (22.7kg). The parts were then molded on a production tool.

As described above, samples of the TPE compositions were tested fortensile strength, hardness, compression set before and afterautoclaving, ultimate elongation, and tensile stress at elongation of100%, 200%, and 300%. The resealability of the samples was comparedagainst each other and given a relative ranking for reseal. The testresults are set forth in Table 2 below.

TABLE 2 Properties of TPE compositions TPE Compositions A B C D Kraton1633 100 75 50 Kraton 1651 25 50 100 Total Parts SBC 100 100 100 100Purell HP 570M 27 27 27 27 Gray 3239L 3.9 3.9 3.9 3.9 Primol 352 160 160160 160 Omyacarb 2-GU 96 96 96 96 Irganox 1010 0.195 0.195 0.195 0.195Irganox PS 800 0.78 0.78 0.78 0.78 Total Parts 387.875 387.875 387.875387.875 Physical Properties Hardness, Shore A 45 42 40 42 Compressionset (CS), 70° C., % 20 23 29 25 Autoclave CS, Cool under compression, %70 77 87 76 Autoclave CS, Cool w/o compression, % 50 50 62 49 TensileStrength, psi (N/cm²) 1260 (870) 1130 (780) 930 (640) 960 (660) %Elongation 890 910 880 840 Mod100%, psi (N/cm²) 140 (97) 120 (83) 120(83)  120 (83)  Mod200%, psi (N/cm²)  190 (130)  160 (110) 170 (120) 160(110) Mod300%, psi (N/cm²)  250 (170)  210 (140) 210 (140) 210 (140) IVSpike Reseal Test Results Needle reseal rating: number of samples, Port1 0: 16/16 0: 12/16 0: 14/16 0: 13/16 200 mbar (20 kPa), beforeAutoclave 1: 4/16 1: 2/16 1: 3/16 Port 2 0: 16/16 0: 11/16 0: 14/16 0:12/16 1: 4/16 1: 2/16 1: 4/16 Needle reseal rating: number of samples,Port 1 0: 12/16 0: 13/16 0: 15/16 0: 15/16 450 mbar (45 kPa), beforeAutoclave 1: 4/16 1: 3/16 1: 1/16 1: 1/16 Port 2 0: 14/16 0: 10/16 0:14/16 0: 12/16 1: 2/16 1: 6/16 1: 2/16 1: 4/16 Needle reseal rating:number of samples, Port 1 0: 12/16 0: 9/16 0: 9/16 0: 11/16 200 mbar (20kPa), after Autoclave 1: 4/16 1: 7/16 1: 6/16 1: 2/16 2: 1/16 2: 2/16 4:1/16 Port 2 0: 10/16 0: 10/16 0: 13/16 0: 6/16 1: 6/16 1: 5/16 1: 2/161: 8/16 2: 1/16 2: 1/16 2: 2/16 Needle reseal rating: number of samples,Port 1 0: 12/16 0: 13/16 0: 11/16 0: 11/16 450 mbar (45 kPa), afterAutoclave 1: 4/16 1: 2/16 1: 4/16 1: 2/16 2: 1/16 1: 2/16 2: 2/16 4:1/16 Port 2 0: 9/16 0: 12/16 0: 10/16 0: 4/16 1: 7/16 1: 2/16 1: 4/16 1:7/16 2: 2/16 2: 2/16 2: 2/16 3: 1/16 4: 2/16

Table 2 demonstrates the effect of molecular weight of the SEBS blockcopolymer on the reseal properties of the TPE compositions after IVspike puncture. It can be seen that while similar reseal properties wereexhibited by all four samples A-D before autoclaving, the TPEcompositions containing the high molecular weight (greater than about200,000 Daltons) SEBS exhibited superior reseal properties afterautoclaving relative to the TPE compositions containing lower molecularweight SEBS. Such a trend was observed regardless of the internalpressure in the bottle. Further, the resealability after autoclavingdecreased with an increase in the amount of lower molecular weight(KRATON® 1651) polymer. Composition A, containing 100 parts of the highmolecular weight KRATON® 1633 polymer, provided the best resealproperties before and after autoclaving.

Example 2 TPE Compositions E-F

Two different TPE compositions, labeled as E and F, were formed from ablend of a high molecular weight SEBS block copolymer, a polypropylene,a colorant, a mineral oil, and stabilizer in the amounts shown in Table3 below. These compositions differed only in the presence (incomposition F) or absence (in composition E) of talc (Mistron CB) as afiller. Mixing of the compositions were performed as described above.The test results for tensile strength, compression set, hardness,elongation, and reseal, as described above, are set forth in Table 3below.

TABLE 3 Properties of TPE Compositions Sample # E F Kraton 1633 100 100Purell HP 570M 27 27 Gray 3239L 2.8 3.4 Primol 352 150 160 Mistron CB 50Irganox PS 800 0.56 0.68 Total 280.36 341.08 Physical PropertiesHardness, Shore A 42 44 Compression Set (CS), 26 22 70° C., % AutoclaveCS, Cool under 70 69 compression, % Autoclave CS, Cool w/o 50 54compression, % Tensile Strength, psi (N/cm²) 1810 (1250) 1370 (940) %Elongation 850 (580) 840 (580) Mod100%, psi (N/cm²) 150 (100) 170 (120)Mod200%, psi (N/cm²) 210 (140) 270 (190) Mod300%, psi (N/cm²) 280 (190)350 (240) IV Spike Reseal Test Results Needle reseal rating: Port 1 0:30/30 0: 30/30 number of samples, Port 2 0: 30/30 0: 30/30 200 mbar (20kPa), before Autoclave Needle reseal rating: Port 1 0: 29/30 0: 30/30number of samples, 1: 1/30 450 mbar (45 kPa), Port 2 0: 30/30 0: 30/30before Autoclave Needle reseal rating: Port 1 0: 28/30 0: 30/30 numberof samples, 1: 2/30 200 mbar (20 kPa), Port 2 0: 27/30 0: 30/30 afterAutoclave 1: 3/30 Needle reseal rating: Port 1 0: 22/30 0: 30/30 numberof samples, 1: 5/30 450 mbar (45 kPa), 2: 3/30 after Autoclave Port 2 0:23/30 0: 30/30 1: 3/30 2: 3/30 3: 1/30

Table 3 demonstrates the effect of filler on the IV spike reseal of theresulting composition. It can be seen that inclusion of a filler (inComposition F) improved resealability, particularly after autoclaving.

Through extensive and intensive experimentation, it has been foundaccording to the present invention that a thermoplastic elastomericarticle having excellent resealability, high tensile strength, and ahardness of less than about 80 Shore A can be formulated by including ahydrogenated SBC having a particular high molecular weight. Inparticular, blending a hydrogenated SBC with a molecular weight greaterthan about 200,000 Daltons with a polypropylene, mineral oil, and fillerprovides for a TPE article with a hardness less than about 80 Shore A,preferably less than about 65 Shore A, more preferably less than about50 Shore A, while maintaining adequate temperature stability,moldability, tear strength, and tensile strength characteristics. Ingeneral, a softer material is more desirable for sealing purposes. Inaddition, such a TPE composition maintains its properties, includingreseal properties, after autoclaving.

In another embodiment, the present invention provides for a resealablearticle manufactured from a thermoplastic elastomer as described above.Resealable articles that may be produced include, without limitation,penetrable closures, including septa, caps and plugs, such as formedical containers, and the like. These articles are particularlydesirable in the medical and scientific research fields due to theirresealable properties, even after autoclaving.

The invention also relates to a method for preventing leakage in apunctured elastomeric article. The method involves providing anelastomeric article comprising a thermoplastic elastomer composition aspreviously described, puncturing the article by inserting a sharpobject, such as a needle, cannula, or IV spike, and removing the sharpobject. Due to the resealable nature of the TPE composition used toproduce the elastomeric article, the article reseals itself such that noleakage occurs from the punctured article. This property is observedregardless of the nature of the sharp object, and objects made of metal,plastic or other materials and having varying diameters may be used topuncture the elastomeric article.

The ability to produce a punctured elastomeric article with no leakageis significant. In the medical and scientific fields in particular, itis often necessary to puncture an elastomeric closure, such as an IVbottle cap, by inserting a sharp object, such as a cannula, in order totransfer fluid through the closure. Following removal of the sharpobject from the inventive elastomeric article, the opening formed fromthe sharp object reseals automatically, thus reforming a continuous sealwith no leakage. Leakage from such seals would be undesirable andpotentially dangerous to a patient, healthcare worker, or scientist.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined by the appended claims.

I claim:
 1. A resealable article comprising a thermoplastic elastomercomposition comprising a blend of: a hydrogenated styrenic blockcopolymer having a number average molecular weight greater than about200,000 Daltons; a polypropylene; a mineral oil; and at least onefiller; wherein the thermoplastic elastomer composition has a hardnessof less than about 80 Shore A.
 2. The article according to claim 1,wherein the thermoplastic elastomer composition comprises about 100parts of the hydrogenated styrene block copolymer, about 5 to 50 pph ofthe polypropylene, about 10 to 400 pph of the mineral oil, and about 10to 120 pph of the at least one filler.
 3. The article according to claim1, wherein the hydrogenated styrenic block copolymer is selected fromthe group consisting of a SEBS (styrene-ethylene-butylene-styrene) blockcopolymer, a SIPS (styrene-isoprene-styrene) block copolymer, and aSEEPS (styrene-ethylene-(ethylene-propylene)-styrene) block copolymer.4. The article according to claim 1, wherein the article is selectedfrom the group consisting of a septum, a cap, a plug, a closure, and astopper.
 5. The article according to claim 1, wherein the articlereseals itself so as to exhibit no leakage after puncture.
 6. Thearticle according to claim 1, wherein the thermoplastic elastomercomposition is autoclavable.